The autonomic nervous system and the cardiovascular system are highly integrated whereby a change to one system generally affects the other system. The autonomic nervous system extends across the body and affects the cardiovascular system through both intracardiac and extracardiac mechanisms. For example, arterial baroreceptors may be considered part of an extracardiac parasympathetic mechanism while cardiac ganglia may be considered part of intracardiac parasympathetic and sympathetic mechanisms.
With respect to intracardiac mechanisms, various studies indicate that electrical, mechanical or chemical stimulation of epicardial “fat pads” can have a profound affect on the cardiovascular system. These so called “fat pads” may be more appropriately described as neural plexuses or subplexuses that are highly innervated with parasympathetic and sympathetic nerves. However, correspondence is not straightforward between autonomic pathways and cardiac behavior. For example, uncertainty exists as to on-set of arrhythmias and autonomic nerve activity or a lack thereof. Various exemplary methods, devices, systems, etc., described herein aim to understand better the relationship between autonomic pathways and atrial arrhythmias and to use such understanding for delivery of anti-arrhythmia therapies.